Viscosity and diffusivity in melts: from unary to multicomponent systems

• Published in: Philosophical magazine (Abingdon, England) Vol. 94; no. 14; pp. 1552 - 1577
• Main Authors: Chen, Weimin, Zhang, Lijun, Du, Yong, Huang, Baiyun
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 13.05.2014
• Subjects: Alloys; Aluminum; Aluminum base alloys; Condensed matter: structure, mechanical and thermal properties; diffusion; Diffusion in solids; Diffusive momentum transport (including viscosity of liquids); Diffusivity; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Liquids; Mathematical models; Melts; Physics; Solubility, segregation, and mixing; phase separation; Sutherland equation; transport properties; Transport properties of condensed matter (nonelectronic); Viscosity; Viscosity; Temperature dependence; Vacancies; Liquid metals; Radioactive tracers; Diffusivity; Calculation methods; Impurities; Multiple system; Size effect; Arrhenius equation; Diffusion; Reliability; Depth profiles; Concentration distribution; Melts
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786435.2014.890755

Viscosity and diffusivity, two important transport coefficients, are systematically investigated from unary melt to binary to multicomponent melts in the present work. By coupling with Kaptay's viscosity equation of pure liquid metals and effective radii of diffusion species, the Sutherland equation is modified by taking the size effect into account, and further derived into an Arrhenius formula for the convenient usage. Its reliability for predicting self-diffusivity and impurity diffusivity in unary liquids is then validated by comparing the calculated self-diffusivities and impurity diffusivities in liquid Al- and Fe-based alloys with the experimental and the assessed data. Moreover, the Kozlov model was chosen among various viscosity models as the most reliable one to reproduce the experimental viscosities in binary and multicomponent melts. Based on the reliable viscosities calculated from the Kozlov model, the modified Sutherland equation is utilized to predict the tracer diffusivities in binary and multicomponent melts, and validated in Al-Cu, Al-Ni and Al-Ce-Ni melts. Comprehensive comparisons between the calculated results and the literature data indicate that the experimental tracer diffusivities and the theoretical ones can be well reproduced by the present calculations. In addition, the vacancy-wind factor in binary liquid Al-Ni alloys with the increasing temperature is also discussed. What's more, the calculated inter-diffusivities in liquid Al-Cu, Al-Ni and Al-Ag-Cu alloys are also in excellent agreement with the measured and theoretical data. Comparisons between the simulated concentration profiles and the measured ones in Al-Cu, Al-Ce-Ni and Al-Ag-Cu melts are further used to validate the present calculation method.